1. Field of the Invention
The present invention relates to image quality control processing in an image forming apparatus, and, more particularly to improvement of accuracy of the image quality control processing.
2. Description of the Related Art
In an image forming apparatus such as a color MFP, a gray image area other than characters in an output image at the time of copy processing and print processing is often formed by mixing toners of four colors, yellow, magenta, cyan, and black. However, when the balance of toner quantities of the respective colors is collapsed because of influences of types of sheets onto which toner images are outputted, variation of the apparatus, and the like, this gray portion changes to a colored gray and is extremely deteriorated in appearance. Colors equal to or lower in order than so-called secondary colors such as R, G, and B may also change to colors with a color balance collapsed depending on types of output sheets because of a problem of transferability and the like. When the color balance is collapsed in this way, conventionally, the color balance is adjusted using functions such as color balance adjustment.
However, since the color balance adjustment is manual adjustment, the color balance adjustment takes time. Even if the color balance is adjusted with effort, when a printer gamma characteristic fluctuates because of aged deterioration and the like, the adjustment has to be performed again every time the fluctuation occurs. Therefore, the control is extremely complicated.
Moreover, even if the adjustment of the color balance is performed as described above, since a type of a sheet as a recording medium is changed commonly, in the conventional color balance adjustment method, it is practically difficult to accurately perform the adjustment of the color balance according to various situations.